The present invention relates generally to a high-frequency circuit package which prevents leakage of electromagnetic waves between a high-frequency circuit and another circuit. More specifically, the invention relates to a high-frequency circuit package which prevents electromagnetic waves produced by a high-frequency circuit from exerting an unfavorable influence upon other circuits and/or preventing electromagnetic waves produced from other circuits from exerting an unfavorable influence upon the high-frequency circuit.
Generally, it is known to install a high-frequency circuit within a high-frequency circuit package in order to prevent electromagnetic waves produced by the high-frequency circuit from exerting an unfavorable influence on other circuits or to prevent electromagnetic waves produced by other circuits from exerting unfavorable influence on the high-frequency circuit. FIG. 1 shows a conventional high frequency circuit package 100. The high-frequency circuit package 100 generally comprises a conductive substrate 102, a shielding wall 104 and a shielding case 106. The shielding wall 104 projects upwards from the upper surface of the conductive substrate 102 and surrounds an essentially rectangular space. The shielding case 106 is arranged on the shielding wall 104 to define therein a shielding chamber 108.
A high-frequency circuit 110 comprising an integrated circuit 112, a semiconductor device 114 and so forth, is packaged in the shielding chamber 108. Input and output signals between the high-frequency circuit 110 and external circuits are performed via leads 116 provided in the shielding wall 104. In addition, input and output of continuous current between the high-frequency circuit 110 and external circuits is accomplished via leads 118 provided in the shielding wall 104.
In this conventional package, since high-frequency circuits having different functions from each other cannot be packaged in the same shielding chamber, one package houses therein only one high-frequency circuit. In order to connect a plurality of high-frequency circuits 110 to each other, the respective packages 110 secured to a main substrate 120 must be connected to each other by means of microstrip lines 122, as shown in FIG. 2. For that reason, a disadvantage arises in that the space for housing therein all of the circuits becomes great, and thus packaging density is low.
In addition, since one package can house therein only one high-frequency circuit 110 as mentioned above, two related high-frequency circuits 110 having different functions from each other, e.g., an oscillating circuit and an amplifying circuit, must be housed within separate packages 100, respectively. Therefore, the disadvantage arises in that the number of electrical connections of the packages 100 to each other becomes great so that reliability of the circuits decreases.